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<title>Using poly_int with C++ arithmetic operators (GNU Compiler Collection (GCC) Internals)</title>

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Next: <a href="wi-arithmetic-on-poly_005fints.html" accesskey="n" rel="next"><code class="code">wi</code> arithmetic on <code class="code">poly_int</code>s</a>, Up: <a href="Arithmetic-on-poly_005fints.html" accesskey="u" rel="up">Arithmetic on <code class="code">poly_int</code>s</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html" title="Index" rel="index">Index</a>]</p>
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<h4 class="subsection" id="Using-poly_005fint-with-C_002b_002b-arithmetic-operators-1"><span>10.4.1 Using <code class="code">poly_int</code> with C++ arithmetic operators<a class="copiable-link" href="#Using-poly_005fint-with-C_002b_002b-arithmetic-operators-1"> &para;</a></span></h4>

<p>The following C++ expressions are supported, where <var class="var">p1</var> and <var class="var">p2</var>
are <code class="code">poly_int</code>s and where <var class="var">c1</var> and <var class="var">c2</var> are scalars:
</p>
<div class="example smallexample">
<pre class="example-preformatted">-<var class="var">p1</var>
~<var class="var">p1</var>

<var class="var">p1</var> + <var class="var">p2</var>
<var class="var">p1</var> + <var class="var">c2</var>
<var class="var">c1</var> + <var class="var">p2</var>

<var class="var">p1</var> - <var class="var">p2</var>
<var class="var">p1</var> - <var class="var">c2</var>
<var class="var">c1</var> - <var class="var">p2</var>

<var class="var">c1</var> * <var class="var">p2</var>
<var class="var">p1</var> * <var class="var">c2</var>

<var class="var">p1</var> &lt;&lt; <var class="var">c2</var>

<var class="var">p1</var> += <var class="var">p2</var>
<var class="var">p1</var> += <var class="var">c2</var>

<var class="var">p1</var> -= <var class="var">p2</var>
<var class="var">p1</var> -= <var class="var">c2</var>

<var class="var">p1</var> *= <var class="var">c2</var>
<var class="var">p1</var> &lt;&lt;= <var class="var">c2</var>
</pre></div>

<p>These arithmetic operations handle integer ranks in a similar way
to C++.  The main difference is that every coefficient narrower than
<code class="code">HOST_WIDE_INT</code> promotes to <code class="code">HOST_WIDE_INT</code>, whereas in
C++ everything narrower than <code class="code">int</code> promotes to <code class="code">int</code>.
For example:
</p>
<div class="example smallexample">
<pre class="example-preformatted">poly_uint16     + int          -&gt; poly_int64
unsigned int    + poly_uint16  -&gt; poly_int64
poly_int64      + int          -&gt; poly_int64
poly_int32      + poly_uint64  -&gt; poly_uint64
uint64          + poly_int64   -&gt; poly_uint64
poly_offset_int + int32        -&gt; poly_offset_int
offset_int      + poly_uint16  -&gt; poly_offset_int
</pre></div>

<p>In the first two examples, both coefficients are narrower than
<code class="code">HOST_WIDE_INT</code>, so the result has coefficients of type
<code class="code">HOST_WIDE_INT</code>.  In the other examples, the coefficient
with the highest rank &ldquo;wins&rdquo;.
</p>
<p>If one of the operands is <code class="code">wide_int</code> or <code class="code">poly_wide_int</code>,
the rules are the same as for <code class="code">wide_int</code> arithmetic.
</p>
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